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Concept
Aube (mécanique)
Résumé
A turbine blade is a radial aerofoil mounted in the rim of a turbine disc and which produces a tangential force which rotates a turbine rotor. Each turbine disc has many blades. As such they are used in gas turbine engines and steam turbines. The blades are responsible for extracting energy from the high temperature, high pressure gas produced by the combustor. The turbine blades are often the limiting component of gas turbines. To survive in this difficult environment, turbine blades often use exotic materials like superalloys and many different methods of cooling that can be categorized as internal and external cooling, and thermal barrier coatings. Blade fatigue is a major source of failure in steam turbines and gas turbines. Fatigue is caused by the stress induced by vibration and resonance within the operating range of machinery. To protect blades from these high dynamic stresses, friction dampers are used.
Blades of wind turbines and water turbines are designed to operate in different conditions, which typically involve lower rotational speeds and temperatures.
In a gas turbine engine, a single turbine stage is made up of a rotating disk that holds many turbine blades and a stationary ring of nozzle guide vanes in front of the blades. The turbine is connected to a compressor using a shaft (the complete rotating assembly sometimes called a "spool"). Air is compressed, raising the pressure and temperature, as it passes through the compressor. The temperature is then increased by combustion of fuel inside the combustor which is located between the compressor and the turbine. The high-temperature, high-pressure gas then passes through the turbine. The turbine stages extract energy from this flow, lowering the pressure and temperature of the gas and transfer the kinetic energy to the compressor. The way the turbine works is similar to how the compressor works, only in reverse, in so far as energy exchange between the gas and the machine is concerned, for example.
Source officielle
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